In orthopedics, rotational deformities of the bone along the lower portions of an individual can change the planar orientation of various respective reference planes for the hip, knee and ankle. For example, abnormal angulation of the femoral neck with respect to the transcondylar axis of the knee is referred to as femoral anteversion. In general, rotational deformities as discussed above may be defined as an abnormal angulation of a bone relative to a longitudinal axis.
It is very common in infants to be born with femoral anteversion due to the position of the fetus inside the womb during pregnancy and can occur in up to 10% of children. In fact, femoral anteversion is the most common cause of children walking with their toes inward (in-toeing) in children older than 3 years of age. Although most rotational bone abnormalities, such as femoral anteversion, are resolved under normal growth and development, a small percentage of cases will continue to suffer from a residual rotational deformity that may later require surgical correction.
One common method of surgical bone realignment to address femoral anteversion is by performing an osteotomy procedure which requires cutting of the bone followed by its realignment to the correct bone orientation. However, osteotomy procedures require making a large incision to create access to the bone for the surgeon to perform the bone cutting and realignment, thereby making the procedure substantially invasive. In addition, the procedure can cause disruption of the adjacent musculature surrounding the bone as well as possibly damaging the neurovascular structures. Procedures to cut and realign bones are associated with a long and painful rehabilitation period that can last several months. The cut bone ends may not heal adequately and in such cases, further surgery may be necessary. Implant failure is also a well documented complication of osteotomies. Another concern is the accidental damage to the growth plate that can occur during the surgical realignment procedure, which can later inhibit healthy and normal limb growth. As such, current surgical bone realignment apparatuses and methods require a relatively invasive procedure be performed to correct rotational bone deformities. An alternative to invasive osteotomies is the use of guided growth through a minimally invasive device.